NullPointerException when deleting Object

Hi all,

I have a strange problem with an Application I have to fix.
I have a list of objects derived from EOGenericRecord which have several
Relationships. Whenn I call editingContext.deleteObject(o) and
editingContext.saveChanges() I get a NullPointerException. The important
part of the stack trace is pasted below.
Now, when I call the list of the objects again, and try to delete the Object
once more, it works. 
Can anyone help me with this Problem? Would be great if anybody has an idea.

Thanks,
 Philipp


java.lang.NullPointerException
at
com.webobjects.foundation._NSStringUtilities.concat(_NSStringUtilities.java:
213)
	at
com.webobjects.eoaccess.EOSQLExpression._aliasForRelatedAttributeRelationshi
pPath(EOSQLExpression.java:264)
	at
com.webobjects.eoaccess.EOSQLExpression.joinExpression(EOSQLExpression.java:
1168)
	at
com.webobjects.eoaccess.EOSQLExpression.prepareSelectExpressionWithAttribute
s(EOSQLExpression.java:1033)
	at
com.webobjects.jdbcadaptor.JDBCExpression.prepareSelectExpressionWithAttribu
tes(JDBCExpression.java:273)
	at
com.webobjects.eoaccess.EOSQLExpressionFactory.selectStatementForAttributes(
EOSQLExpressionFactory.java:219)
	at
com.webobjects.jdbcadaptor.JDBCChannel.selectAttributes(JDBCChannel.java:178
)
	at
com.webobjects.eoaccess.EODatabaseChannel._selectWithFetchSpecificationEditi
ngContext(EODatabaseChannel.java:879)
	at
com.webobjects.eoaccess.EODatabaseChannel.selectObjectsWithFetchSpecificatio
n(EODatabaseChannel.java:216)
	at
com.webobjects.eoaccess.EODatabaseContext._objectsWithFetchSpecificationEdit
ingContext(EODatabaseContext.java:3206)
	at
com.webobjects.eoaccess.EODatabaseContext.objectsWithFetchSpecification(EODa
tabaseContext.java:3347)
	at
com.webobjects.eocontrol.EOObjectStoreCoordinator.objectsWithFetchSpecificat
ion(EOObjectStoreCoordinator.java:539)
	at
com.webobjects.eocontrol.EOEditingContext.objectsWithFetchSpecification(EOEd
itingContext.java:4075)
	at
com.webobjects.eoaccess.EODatabaseContext.objectsForSourceGlobalID(EODatabas
eContext.java:4261)
	at
com.webobjects.eocontrol.EOObjectStoreCoordinator.objectsForSourceGlobalID(E
OObjectStoreCoordinator.java:682)
	at
com.webobjects.eocontrol.EOEditingContext.objectsForSourceGlobalID(EOEditing
Context.java:3926)
	at
com.webobjects.eoaccess.EODatabaseContext._fireArrayFault(EODatabaseContext.
java:4428)
	at
com.webobjects.eoaccess.EOAccessArrayFaultHandler.completeInitializationOfOb
ject(EOAccessArrayFaultHandler.java:70)
	at
com.webobjects.eocontrol._EOCheapCopyMutableArray.willRead(_EOCheapCopyMutab
leArray.java:38)
	at
com.webobjects.eocontrol._EOCheapCopyMutableArray.count(_EOCheapCopyMutableA
rray.java:92)
	at
com.webobjects.eocontrol._EOCheapCopyArray._setArray(_EOCheapCopyArray.java:
60)
	at
com.webobjects.eoaccess._EOCheapCopyHandler.completeInitializationOfObject(E
OAccessArrayFaultHandler.java:151)
	at
com.webobjects.eocontrol._EOCheapCopyArray.willRead(_EOCheapCopyArray.java:3
2)
	at
com.webobjects.eocontrol._EOCheapCopyArray.count(_EOCheapCopyArray.java:87)
	at
com.webobjects.eoaccess.EODatabaseContext.nullifyAttributesInRelationshipSou
rceObjectDestinationObjects(EODatabaseContext.java:5165)
	at
com.webobjects.eoaccess.EODatabaseContext.recordChangesInEditingContext(EODa
tabaseContext.java:6056)
	at
com.webobjects.eocontrol.EOObjectStoreCoordinator.saveChangesInEditingContex
t(EOObjectStoreCoordinator.java:412)
	at
com.webobjects.eocontrol.EOEditingContext.saveChanges(EOEditingContext.java:
3187)
[...]